1. Field of the Invention
This invention relates to a lockup clutch to be used in a torque converter, and more particularly to a lockup clutch for use in a four-element (two-turbine) torque converter.
2. Description of the Prior Art
A torque converter comprising two turbines is disclosed in the U.S. Pat. No. 2,903,912. In this construction, a linking plate (support) for linking the outer circumference of the first turbine and its output hub is located between the shell and front cover (the input part of torque converter) of the second turbine. A lockup clutch is not disposed.
On the other hand, lockup clutches to be assembled into a torque converter having one turbine are disclosed in the U.S. Pat. No. 4,240,532 the Japanese Utility Model Publication No. 61-28126, the Japanese Utility Model Application No. 61-170593 and U.S. Pat. No. 4,903,803 corresponding thereto. The clutch disc of these lockup clutches is located between the turbine and the front cover.
According to the construction in the U.S. Pat. No. 4,240,532 or the Japanese Utility Model Publication No. 61-28126, the output member of the clutch disk is welded to the shell of the turbine. In the Japanese Utility Model Application No. 61-170593, the output member of the clutch disc is fixed to the hub which is an output part of the turbine.
By combining the above structures, when it is attempted to compose a four-element torque converter having a lockup clutch, the following problems are encountered.
That is, in any one of the above clutch discs, because an exclusive member is used as the output member, when such clutch disc is incorporated into a four-element torque converter having a large number of component parts, the total number of parts is further increased, the dimension becomes larger, and the assembling takes more time and labor.